Engine/Transmission (1994 - 1998) no overdrive

[LVJUNIOR]

My brother has a 96 auto 2wd that won't shift into overdrive. He has replaced the governor solenoid the temperature transducer, the overdrive lockup solenoid assembly, and hard wired a switched ground to the OD wire where it plugs into the PCM.



He says he is getting lockup in third.



What should I check next.

 

[SFPADGETT]

Does the "hard wired" switch make it shift into OD?

Is the grounded switch wire at the transmission or at the PCM? If at the PCM, I would recommend to change it to the plug in connector on the transmission.



(I had a bad ground signal wire from the PCM to the plug in connector on the transmission several months back. The wire would "ohm" as good, but it would not carry the voltage for the solenoid to engage. Search my previous post "Lost Overdrive" and see items that I replaced/checked)



If the switch does make the transmission shift into OD, then the problem is outside the transmission, if not, it is inside the transmission. Either one has a list of items to check. Let us know and the folks here can point you in the right direction.

 

[Missouri Mule]

From 96 Service Manual (factory)

No 3-4 up shift.

1. Dash o/d switch in "off position".

2. OD circuit fuse blown.

3. OD switch wire shorted/open cut.

4. Distance or coolant sensor malfiunction.

5. TPS malfunction.

6. Neutral switch to PCM wire shorted/cut.

7. PCM malfunction.

8. OD solenoid shorted/open

9. Solenoid feed orfice in valve body blocked.

10. OD clutch failed.

11. Hydraulic pressure low.

12. Valve body valve stuck.

13. OD piston incorrect spacer.

14. OD piston seal failure.

15. OD check valve/orifice failed.

 

[LVJUNIOR]

SFPADGETT

This truck is my brothers so I am trying to get this sorted out with a combination of first hand and second hand information.



I had him hardwire the switch at the trans instead of the PCM and still no overdrive. So, I assume it is in the trans. He has adjusted the rear band as well as the solenoids and other parts I mentioned earlier. I am pretty handy with a toolbox and a factory service manual but when it came to a transmission for my 12v I called Goerend (Just got a call saying it shipped today. . yeah) so some of the tests are a little foreign to me.



I did read your original thread however and saw you had found the wire as the culprit



as for the other reply, here is what I have done with the things you listed



1. Dash o/d switch in "off position". checked ok

2. OD circuit fuse blown. checked ok

3. OD switch wire shorted/open cut. checked ok

4. Distance or coolant sensor malfiunction.

5. TPS malfunction. checked ok

6. Neutral switch to PCM wire shorted/cut.

7. PCM malfunction. checked no codes

8. OD solenoid shorted/open new replacement

9. Solenoid feed orfice in valve body blocked. not checked

10. OD clutch failed.

11. Hydraulic pressure low.

12. Valve body valve stuck.

13. OD piston incorrect spacer.

14. OD piston seal failure.

15. OD check valve/orifice failed.



I have not checked the items listed but not commented on.



My brother did tell me when he replaced the overdrive solenoid he felt the piston seemed to be looser than he expected. I did not see this for myself so I don't know how loose it was. Is the overdrive piston supposed to be a snug fit in the bore?

 

[SFPADGETT]

It could be any of the items listed above, but from past experience I would lean toward the OD Piston Seal (very large o-ring). I have seen it fail in a lot of transmissions (both ours and friends).

 

[LVJUNIOR]

He went to the dealer today to get the seal. no dice. you have to buy the whole seal kit and there are none in town. It should be here in a few days.

 

[LVJUNIOR]

Replaced the OD piston and seals. Still no overdrive

 

[Dirty&harry]

Isn't there a plugin on transmission where you can apply a pressuregauge and measure the hydraulic oilpressure to the OD circiut,or am I mistaken??

 

[LVJUNIOR]

I have been so busy that I have not had much time to get my hands on this one and I don' think he has a pressure gauge.

 

[SFPADGETT]

There are 4 ports on the transmission for pressure checks. They are listed in Factory Service Manual along with the range of the readings. Sounds like the OD unit may need to be rebuilt, and if so, you might as well do the rest of the transmission at the same time. How many miles on the transmission?

 

[LVJUNIOR]

It was supposedly rebuilt within the last two years locally. But I have not heard of a transmission shop in las Vegas that was remotely competent. A full rebuild would bankrupt him right now. I smelled hs fluid yesterday and it is pretty nasty

 

[LVJUNIOR]

Just got a call from my brother and he told me he replaced the 3-4 accumulator piston not the OD piston. How hard is it to get to the OD piston. Can it be done on the truck

 

[Dirty&harry]

The 47RE transmission consist of two parts:

The main section(Front part)the overdrive unit(rear part of atomatic)

To get to the overdrivepiston,you need to divide the transmission in the middle.

The OD piston goes along the transmission,not anything that goes upon above the pan.

Above the pan,you only find the kickdownband-piston,the reverce-pistond and this accumulator piston you mensioned... .



It is quit easy to replace the OD piston seal as you can divide the transmission in two sections... .



However,I do not belive the problem is in the pistonseal... .



Question:

Has he had problems with the lock up earlyer?

Have there been problems during down**** from 2nd to 1st gear??



When the fluid runs dirty,and the filter beginning to be clogged,the first sign will be you loose lockup and overdrive.

Altso,some unregular downshifting from 2nd to 1. gear can altso happen.

 

[LVJUNIOR]

Question:

Has he had problems with the lock up earlyer?

Have there been problems during down**** from 2nd to 1st gear??



When the fluid runs dirty,and the filter beginning to be clogged,the first sign will be you loose lockup and overdrive.

Altso,some unregular downshifting from 2nd to 1. gear can altso happen.

I am not sure about the lockup before but I know it is working now. when he dropped the pan originally the filter was a black mess and the fluid was rank. He dropped the pan again at my house and it still smelled burnt after only around 40 miles. He changed the fluid again and he said it still stinks but I haven't seen it personally since the last fluid change.



I am not sure what is burning the fluid but wouldn't it still shift into overdrive and then slip like crazy if it was an overdrive clutch

 

[Dirty&harry]

The black mess(deposits) probably hailing from burned clutches in front and rear drum.

(there are 4 clutch-packages in 47RE,from front to back:Front drum,rear drum,overdive clutch and direct clutch)and perhaps from the 2. gear apply band altso. You see the lower part of the band if you remove the valvebody.



I assume your brother run with the OEM converter,where there is no drain plug.

Still,even after two oilcanges,there will still be a lot of polluted oil in the converter and the system.



1. question:Have you removed the check ball in the cooling line hose??



I suggest you start all over again with desmounting the valvebody from the transmission.

Clean valvebody as good as you can.

You can remove the LU and OD solenoids and a cover to the opposite site and clean the slides and the orifis. Pressurised air would be helpful here.

Altso,check that the main pressure regulator is clean and slides smooth.

If the pressure regulator not working proparly,you risk loss of pressure-loss of holding force on clutches and burning clutches again.



When you have filled up with new oil,open the back-feeding line from oilcooler.

Then start the engine. The transmission oilpump will now pump new oil into the converter,and the old,polluted oil that is inside the converter will be pumped threw the cooling line and out threw the open line.

Wait untill it is comming new fresh oil out of the line,then stop engine.



Like this you will get most of the polluted oil out of the system.



And I suppose you replace the filter with a new one wen you do this.



I have drainplug in my converter. I changed oil and filter three times after brakedown i my transmission,and still I have problems with particles and dirt in the system...



You might as well bye a shift kit and apply to the valve body when you remove it from transmission... .

 

[LVJUNIOR]

sounds like you've done this before. You are very helpful. I will get this information to him ASAP